1. Obi-wan needing the help of the Jedi Brats to figure out why he could not find Kamino in the archives. Come on, could it be more obvious?

2. "Nooooooooo" in Return of the Jedi.

There are more, but I want to hear yours.

The whole point of that youngling scene is for Obi-Wan to see the obvious by looking through the eyes of a child. Later on Windu couldn't see through the eyes of a child to realize Dooku was evil..it serves a strong purpose in the film.

ROTJ ground battle. The ewoks do cool things like lassoing a speeder bike to make it crash into a tree. That's a good thing. Thrown rocks knock down Stormtroopers in armor? That's a bad thing. It should have been more of the former and less of the latter.

Mace's conversation with Anakin - why not just let him come!? Or tell him to go do something to keep him occupied. Or wait for like 3 hours and take various others to confront him. Others have given valid reasons but it still gets to me.

The ridiculous deaths of Kit Fisto and Saesee Tiin

The horrible zoom-in sequence when Mace goes to kill Palpatine

Mace's scream at having his hand cut off

Anakin's 5 minute flip from ratting out the sith to pledging allegiance to them